1. Field of the Invention
The present invention relates to biometric sensor optimization. More particularly, the present invention relates to optimizing performance of a biometric sensor.
2. Related Art
In the field of biometric image analysis, traditional techniques sample an image, such as a fingerprint, as the image is sensed by a sensing mechanism. This sensing mechanism, such as a pressure and/or acoustic impedance-sensitive piezoelectric fingerprint sensor, captures images of the fingerprint. Ridges and valleys of the fingerprint vary pressure and/or acoustic impedance on different parts of the piezoelectric sensor to form light and dark portions of the captured image.
The sensing ability of conventional biometric sensors, and their processing circuits, suffers from many shortcomings due to effects of changing environmental conditions, sensor manufacturing variations, and conditions of the fingers themselves. These conventional biometric sensors are also susceptible to temperature variations, air pressure, and humidity. These changes lead to problems like variations in the sensor's resonant frequency and sensor accuracy, thus degrading sensor performance and resulting in a loss of information.
Conventional biometric sensors also suffer from manufacturing variations. Manufacture of piezoelectric sensors requires creating an array of piezoelectric sensing elements. The manufacturing process varies thickness from sensor to sensor, affecting response of the sensing elements to finger pressure and/or acoustic impedance and thus sensor performance. These variations in resonant frequency degrade sensor performance and lead to changes in signal level and bias of the sensor's output that are unmitigated by conventional processing circuits.
What is needed, therefore, is a biometric sensor optimization technique that reduces the effects of the environment, manufacturing variations, and finger conditions as noted above in conventional approaches.